System and method for multiplexing control and data channels in a multiple input, multiple output communications system

ABSTRACT

A system and method for system and method for multiplexing control and data channels in a multiple input, multiple output (MIMO) communications system are provided. A method for transmitting control symbols and data symbols on multiple MIMO layers includes selecting a first set of codewords from Ncw codewords, distributing control symbols onto the first set of layers, placing data symbols of the first set of codewords onto the first set of layers, placing data symbols of the (Ncw-Ncw1) remaining codewords to remaining layers if Ncw&gt;Ncw1, and transmitting the multiple MIMO layers. The first set of codewords is associated with a first set of layers from the multiple MIMO layers, and the Ncw codewords are to be transmitted simultaneously and the first set of codewords comprises Ncw1 MIMO codewords, where Ncw and Ncw1 are integers greater than or equal to 1. The remaining layers are MIMO layers from the multiple MIMO layers not in the first set of layers.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation application of U.S. Non-Provisionalapplication Ser. No. 12/856,333, filed on Aug. 13, 2010, entitled“System and Method for Multiplexing Control and Data Channels in aMultiple Input, Multiple Output Communications System,” which claims thebenefit of U.S. Provisional Patent Application Ser. No. 61/293,985,filed on Jan. 11, 2010, entitled “System and Method for MultiplexingControl and Data Channels in a Multiple Input, Multiple OutputCommunications System,” which applications are incorporated herein byreference.

TECHNICAL FIELD

The present invention relates generally to wireless communications, andmore particularly to a system and method for multiplexing control anddata channels in a multiple input, multiple output (MIMO) communicationssystem.

BACKGROUND

For 3GPP Rel-8 (commonly referred to as Long Term Evolution (LTE)),broadly speaking, uplink control information may be sent in two ways:(a) without simultaneous transmission of data (i.e., uplink sharedchannel (UL-SCH)); and (b) with simultaneous transmission of UL-SCH.Here we are concerned with (b) where control and data are sent on thesame subframe.

When user equipment (UE) has a valid scheduling grant, network resourcesare assigned for the UL-SCH in a corresponding subframe. In thesubframe, the uplink layer 1 (L1)/layer 2 (L2) control signaling may bemultiplexed with the coded UL-SCH onto a physical uplink shared channel(PUSCH) prior to modulation and discrete Fourier transform (DFT)transform precoding. The control signaling may include hybrid automaticrepeat request (HARQ) acknowledgements and channel status reports.

SUMMARY OF THE INVENTION

These and other problems are generally solved or circumvented, andtechnical advantages are generally achieved, by embodiments of a systemand method for multiplexing control and data channels in a multipleinput, multiple output (MIMO) communications system.

In accordance with an embodiment, a method for transmitting controlsymbols and data symbols on multiple input, multiple output (MIMO)layers is provided. The method includes selecting a first set ofcodewords from N_(cw) codewords, distributing control symbols onto thefirst set of layers, placing data symbols of the first set of codewordsonto the first set of layers, placing data symbols of the(N_(cw)-N_(cw1)) remaining codewords to remaining layers ifN_(cw)>N_(cw1), and transmitting the multiple MIMO layers. The first setof codewords is associated with a first set of layers from the multipleMIMO layers, and the N_(cw) codewords are to be transmittedsimultaneously and the first set of codewords comprises N_(cw1) MIMOcodewords, where N_(cw) and N_(cw1) are integers greater than or equalto 1. The remaining layers are MIMO layers from the multiple MIMO layersnot in the first set of layers.

In accordance with an embodiment, a method for transmitting controlsymbols and data symbols on multiple input, multiple output (MIMO)layers is provided. The method includes constructing one or morecodewords to be simultaneously transmitted over a plurality of MIMOlayers, distributing control symbols over the plurality of MIMO layers,placing data symbols of the one or more codewords onto the plurality ofMIMO layers, and transmitting the multiple MIMO layers.

In accordance with an embodiment, a method for transmitting controlsymbols and data symbols on multiple input, multiple output (MIMO)layers is provided. The method includes selecting a codeword from aplurality of codewords, distributing control symbols onto the subset ofMIMO layers, placing data symbols of the plurality of codewords onto theplurality of layers, and transmitting the multiple MIMO layers. Theplurality of codewords are to be transmitted over a plurality of MIMOlayers, and the selected codeword is to be transmitted over a subset ofMIMO layers of the plurality of MIMO layers.

An advantage of an embodiment is that control signals multiplexed ontomultiple MIMO layers may help with diversity processing gain.

Yet another advantage of an embodiment is that multiplexing the controlsignals onto multiple MIMO layers based on the type, requirements, andnature of the control information is transmitted. For example, CQI/PMIcontrol signals may be mapped onto different MIMO layers or CWs ornumber of MIMO layers than HARQ ACK/NACK or RI.

The foregoing has outlined rather broadly the features and technicaladvantages of the present invention in order that the detaileddescription of the embodiments that follow may be better understood.Additional features and advantages of the embodiments will be describedhereinafter which form the subject of the claims of the invention. Itshould be appreciated by those skilled in the art that the conceptionand specific embodiments disclosed may be readily utilized as a basisfor modifying or designing other structures or processes for carryingout the same purposes of the present invention. It should also berealized by those skilled in the art that such equivalent constructionsdo not depart from the spirit and scope of the invention as set forth inthe appended claims.

BRIEF DESCRIPTION OF THE DRAWINGS

For a more complete understanding of the embodiments, and the advantagesthereof, reference is now made to the following descriptions taken inconjunction with the accompanying drawings, in which:

FIG. 1 is a space diagram of a multiplexing of control and data in LTE;

FIG. 2 is a diagram of a transmitter structure of rank-2 UL transmissionusing two TBs for two transmit antennas in the case of no ACK/NACKspatial bundling without layer shifting;

FIG. 3 is a diagram of a transmitter structure of rank-2 UL transmissionusing two TBs for two transmit antennas in the case of ACK/NACK spatialbundling with layer shifting;

FIG. 4 a is a diagram of a single codeword to a single layer mapping inLTE;

FIG. 4 b is a diagram of a mapping of two codewords to two layers;

FIG. 4 c is a diagram of a mapping of two codewords to three layers;

FIG. 4 d is a diagram of a mapping of two codewords to four layers;

FIG. 4 e is a diagram of a mapping of one codeword to two layers;

FIG. 5 is a space diagram of two MIMO layers containing control and datafrom a single codeword;

FIG. 6 is a space diagram of two MIMO layers containing control and datafrom two codewords;

FIG. 7 is a space diagram of three MIMO layers containing control anddata from two codewords; and

FIG. 8 is a space diagram of two MIMO layers containing control and datafrom two codewords.

DETAILED DESCRIPTION OF ILLUSTRATIVE EMBODIMENTS

The making and using of the embodiments are discussed in detail below.It should be appreciated, however, that the present invention providesmany applicable inventive concepts that can be embodied in a widevariety of specific contexts. The specific embodiments discussed aremerely illustrative of specific ways to make and use the invention, anddo not limit the scope of the invention.

FIG. 1 illustrates space diagram 100 of a multiplexing of control anddata in LTE. As shown in FIG. 1, control and data are multiplexed onto asingle uplink layer. Space diagram 100 may be partitioned into differentzones with the zones carrying different information. Zones hashed with asimilar hashing pattern carry similar information. For example, zone 105may be used to carry a reference signal, e.g., a pilot. While zone 110may be used to carry UL-SCH data, zone 115 may be used to carry channelquality indicator and/or precode matrix indication information, zone 120may be used to carry ACKs/NACKs used in HARQ, and zone 125 may be usedto carry rank indicator information.

Each zone may contain a plurality of resource elements (REs) with anexact number of resource elements assigned to an individual zone beingdependent on factors such as coding and modulation scheme being used,communications system configuration, number of UE operating, and soforth. The proportions of the various zones shown in space diagram 100are not intended to illustrate precise relationships of the amount ofresource elements allocated to the various zones, but to convey arelative relationship and arrangement of the zones.

For 3GPP Rel-10 (commonly referred to as LTE-Advanced (LTE-A)), atransmission block (TB) may be mapped to a MIMO codeword (CW) after achain of processing including channel coding, rate matching, modulation,and so on, the same as in LTE. However, the maximum number of MIMOlayers in LTE-A uplink is increased to four and the maximum number ofMIMO codewords is increased to two.

In contrast to downlink MIMO, uplink (UL) MIMO of LTE-A is consideringadopting layer shifting together with ACK/NACK spatial bundling in theprocessing chain. FIG. 2 illustrates a transmitter structure 200 ofrank-2 UL transmission using two TBs for two transmit antennas in thecase of no ACK/NACK spatial bundling without layer shifting. FIG. 3illustrates a transmitter structure 300 of rank-2 UL transmission usingtwo TBs for two transmit antennas in the case of ACK/NACK spatialbundling with layer shifting.

FIG. 4 a illustrates a single codeword to a single layer mapping in LTE.FIG. 4 b illustrates a mapping of two codewords to two layers. FIG. 4 cillustrates a mapping of two codewords to three layers. FIG. 4 dillustrates a mapping of two codewords to four layers. FIG. 4 eillustrates a mapping of one codeword to two layers. If the design usedin DL LTE is used, then the mapping shown in FIG. 4 e may only be usedfor retransmissions where an initial transmission used two layers tosend the TB. Further, the combinations of codeword (CW) to layer mappingshown in FIG. 4 a through FIG. 4 e can be used for LTE-Advanced uplink.

As stated in TR36.814, “simultaneous transmission of uplink L1/L2control signaling and data is supported through two mechanisms:

-   -   Control signaling is multiplexed with data on PUSCH according to        the same principle as in Rel-8    -   Control signaling is transmitted on physical uplink control        channel (PUCCH) simultaneously with data on PUSCH.”

Although control may be transmitted on PUCCH simultaneously with data onPUSCH, control signaling multiplexing with data on PUSCH is still neededfor at least the following cases:

-   -   Multiplexing data and control on PUSCH reduces CM and hence        increases the coverage.    -   When CQI/PMI/RI and maybe other channel state information is        triggered by PDCCH that assigns UL-SCH transmission, such        control information has to be multiplexed together with data on        PUSCH.

When only one MIMO layer is being used, the same control-datamultiplexing scheme as described for 3GPP Release-8 should be used(shown in FIG. 1). New designs of control-data multiplexing arediscussed below for cases with multiple MIMO layers, e.g., one or morecodewords mapped to two, three, or four MIMO layers (shown in FIGS. 4 bthrough 4 e).

The multiplexing of control-data to multiple MIMO layer PUSCHtransmission may take several approaches: single codeword or allcodewords.

Single codeword rule—Select layers associated with one of the codewordsfor control-data multiplexing. A criteria or rule may be needed toselect an appropriate codeword. The codeword may be selected explicitly(for example, select a first codeword) via higher layer signaling ordynamic physical downlink control channel (PDCCH) signaling.Alternatively, the codeword may be selected implicitly using a) acodeword's modulation and coding scheme (MCS) level as provided in thePDCCH that assigns the PUSCH, b) a codeword's signal plus interferenceto noise ratio (SINR), c) a number of layers occupied by a codeword, d)an impact of a codeword on PUSCH performance, e) HARQ transmissionstatus, for example, initial versus re-transmissions or a combinationthereof.

All codewords rule—Use all the MIMO layers for control-datamultiplexing. When one codeword is mapped to two layers, the singlecodeword strategy degenerates to the all codewords strategy.

The performance comparison and selection for a final solution dependsheavily on whether ACK/NACK spatial bundling (LS/ANB) with layershifting is used for UL MIMO transmissions. Further considerations mayinclude the type of receiver (successive interference cancellation (SIC)versus minimum mean-square error (MMSE)) that an enhanced NodeB (eNB) islikely to implement, whether re-transmission is on one of the codewordsin case of no LS/ANB, size (number of bits) of the control information(relative to that of the PUSCH resource allocated). In addition,different consideration may be needed for CQI/PMI versus ACK/NACK and RIfor diversity and coverage purposes. For example, CQI/PMI may be mappedto different layers or CWs, or a different number of layers or CWs, thanthe ACK/NACK or RI.

Although LTE control information, such as ACK/NACK, RI, CQI/PMI, isdiscussed herein, other control signaling, such as carrier indicators,may be processed in a similar manner in LTE-A.

Control Information on a Single Codeword.

Since control information is important for the proper functioning of acommunications system, they need to be protected as much as possible tothat they may be received by the eNB correctly. Furthermore, the controlinformation is relatively small and is protected by relatively weakcodes, such as block codes and convolutional codes, thus a physicalchannel with better quality should be used to carry the controlinformation.

Therefore, if there are multiple MIMO layers, design considerations mayinclude:

-   -   The control information should be mapped to layers with better        quality. For example, for two codewords mapped to two layers,        assuming that layer two is better than layer one, then the        control information should be mapped to layer two, leaving layer        one completely for data only.    -   It may be simpler for the receiver if the control information is        mapped to layers belonging to a same codeword.    -   If the control information is to be multiplexed with a codeword        X, the control information should be mapped to all layers of        codeword X. Doing so allows the control information to take        advantage of diversity between layers.    -   If the control information is mapped to multiple layers, it        should occupy the same resource elements across the multiple        layers.

Thus for the codeword-to-layer mapping scenarios shown in FIGS. 4 athrough 4 e, the control-data multiplexing is as follows. In the figuresto be discussed below, the illustrated locations of the control signals,e.g., FIGS. 1, 5-8, the amount of resource elements allocated for eachtype of control signaling is for illustration only. As in LTE, thenumber of modulation symbols for each type of control signaling will becalculated as a function of several variables. Then a rule may be usedto assign the modulation symbols to the resource elements till all themodulation symbols are exhausted. The number of modulation symbolsallocated in each layer/slot may vary.

One codeword mapped to one layer: Reuse 3GPP Release-8 design (FIG. 1).

One codeword mapped to two layers: FIG. 5 illustrates a space diagram500 of two MIMO layers containing control and data from a singlecodeword. Control information (contained in zone 505 and zone 506 aswell as zones 510-513) may be multiplexed onto both layers, whereincontrol modulation symbols occupy the same (or approximately the same)resource elements in both layers. As illustrated in FIG. 5, theinformation carried over zones, such as zones 510-513, may betime-division multiplexed with the data. As specified in LTE Rel-8,zones 510-513 may also be used to carry HARQ ACK/NACK information andrank indicator (RI).

Two codewords mapped to two layers: FIG. 6 illustrates a space diagram600 of two MIMO layers containing control and data from two codewords.Map control information to a layer according to single codeword rule asdiscussed previously (zone 605 and zones 615 and 616). Let the layercarrying the control information be referred to as layer X. Within layerX, the multiplexing of control and data reuses the 3GPP Release-8design. Here the control information includes not only CQI, ACK/NACK, RIused in Release-8, but it also includes any new type of controlinformation that may be defined for Release-10 or later, e.g., indicatorfor carrier aggregation and COMP, etc. Zone 610 carries data fromcodeword with control and data, while zone 611 carries data fromcodeword with only data.

Two codewords mapped to three layers: FIG. 7 illustrates a space diagram700 of three MIMO layers containing control and data from two codewords.As shown in FIG. 7, a first codeword (let it be referred to as CW1) ismapped to one layer and a second codeword (let it be referred to as CW2)is mapped to two layers. Clearly, CW2 contains twice as many modulationsymbols as CW1 if control information is excluded. Thus, if controlinformation is punctured into the data modulation symbols, multiplexingcontrol symbols with CW2 may be better than multiplexing with CW1 interms of a number of data modulation symbols being punctured from acodeword. Zone 705 and zones 720 and 721 contain control informationfrom codeword containing control and data, zone 710 contains data fromcodeword containing control and data, and zone 715 contains data fromcodeword containing only data.

Two codewords mapped to four layers: Each codeword is mapped to two MIMOlayers. Let a first codeword where control information resides bedenoted codeword X. Codeword X is selected according to single codewordrule as discussed previously. Within codeword X, multiplexing of controland data may be performed as with codeword CW2 in the case with twocodewords mapped to three layers.

Control Information on all Codewords.

In the situation where control information is contained in allcodewords, then the control information may be always mapped to all MIMOlayers. As discussed herein, all codewords means that there are two ormore codewords. Therefore, situations where one codeword is mapped toone or two layers may not be considered. FIG. 8 illustrates a spacediagram 800 of two MIMO layers containing control and data from twocodewords. As shown in FIG. 8, control information may be mapped to bothlayers, while data from each of the two codewords are mapped to a singlelayer. The mapping of control and data from two codewords to two MIMOlayers as shown in FIG. 8 may have an advantage of maximizing spatialdiversity for the control information as well as better coverage ofcontrol information. Zones 805 and 806 as well as zones 815 through 818carry control information from both codewords, while zone 810 carriesdata from a first codeword and zone 811 carries data from a secondcodeword.

However, resource assignment of control signaling may be difficult dueto separate processing of two transmission blocks. For example, twotransmission blocks may have different modulation orders, therebycausing control information to use two different modulation orders. If aSIC receiver is used, mapping control information to all layers may makeit difficult to implement the cancellation. Additionally, if ACK/NACKspatial bundling with layer shifting is adopted, full or close to fullspatial diversity may be available to each layer, making all codewordmapping even more unattractive.

In 3GPP Release-8, formulas for determining a number of coded symbolsfor HARQ-ACK or rank indicator and channel quality information are:

$\begin{matrix}{Q^{\prime} = {\min\begin{pmatrix}{\left\lceil \frac{O \cdot M_{sc}^{{PUSCH} - {initial}} \cdot N_{symb}^{{PUSCH} - {initial}} \cdot \beta_{offset}^{PUSCH}}{\sum\limits_{r = 0}^{C - 1}\; K_{r}} \right\rceil,} \\{4 \cdot M_{sc}^{PUSCH}}\end{pmatrix}}} \\{and} \\{{Q^{\prime} = {\min\begin{pmatrix}{\left\lceil \frac{\left( {O + L} \right) \cdot M_{sc}^{{PUSCH} - {initial}} \cdot N_{symb}^{{PUSCH} - {initial}} \cdot \beta_{offset}^{PUSCH}}{\sum\limits_{r = 0}^{C - 1}\; K_{r}} \right\rceil,} \\{{M_{sc}^{PUSCH} \cdot N_{symb}^{PUSCH}} - \frac{Q_{RI}}{Q_{m}}}\end{pmatrix}}};}\end{matrix}$wherein K_(r) is the size of code block r, O is the number ofinformation bits for control channel L is the number of MIMO layers,M_(sc) ^(PUSCH) is the scheduled bandwidth for PUSCH transmission in thecurrent sub-frame for the transport block, M_(SC) ^(PUSCH-initial) isthe scheduled bandwidth for PUSCH transmission in the initial sub-frame,N_(symb) ^(PUSCH) is the number of SC-FDMA symbols in the current PUSCHtransmission sub-frame, and N_(symb) ^(PUSCH-initial) is the number ofSC-FDMA symbols per subframe for initial PUSCH transmission.

To extend to multiple layer PUSCH transmissions, the formulas need to beupdated as well. Note that while ACK/NACK, RI, and CQI are used asexamples of control information, similar formula may be used to carryother types of control information, e.g., the indicator for carrieraggregation and COMP, etc. The formulas are not to be interpreted to belimited to any specific control information type. Formulas for thesingle codeword case are shown below.

ACK/NACK (RI) for Single Codeword:

${Q^{\prime} = {\min\begin{pmatrix}{\left\lceil \frac{O \cdot M_{sc}^{{PUSCH} - {initial}} \cdot N_{symb}^{{PUSCH} - {initial}} \cdot N_{layer} \cdot \beta_{offset}^{PUSCH}}{\sum\limits_{r = 0}^{C - 1}\; K_{r}} \right\rceil,} \\{4 \cdot M_{sc}^{PUSCH} \cdot N_{layer}}\end{pmatrix}}},$where N_(layer) is the number of layers for the multiplexing CW. Inaddition, the order of mapping REs across layers need to be defined.

CQI for Single Codeword:

$Q^{\prime} = {{\min\begin{pmatrix}{\left\lceil \frac{\left( {O + L} \right) \cdot M_{sc}^{{PUSCH} - {initial}} \cdot N_{symb}^{{PUSCH} - {initial}} \cdot N_{layer} \cdot \beta_{offset}^{PUSCH}}{\sum\limits_{r = 0}^{C - 1}\; K_{r}} \right\rceil,} \\{{M_{sc}^{PUSCH} \cdot N_{symb}^{PUSCH} \cdot N_{layer}} - \frac{Q_{RI}}{Q_{m}}}\end{pmatrix}}.}$In addition, an order of mapping resource elements across layers need tobe defined.Formulas for the all codeword case are shown below.

ACK/NACK for all Codewords:

$\begin{matrix}{Q^{\prime} = {\min\begin{pmatrix}{\left\lceil \frac{O \cdot \left( {N_{{layer},1} + N_{{layer},2}} \right)}{{N_{{layer},1} \cdot \frac{{MPR}_{1}}{\beta_{1}}} + {N_{{layer},2} \cdot \frac{{MPR}_{2}}{\beta_{2}}}} \right\rceil,} \\{4 \cdot M_{sc}^{PUSCH} \cdot \left( {N_{{layer},1} + N_{{layer},2}} \right)}\end{pmatrix}}} \\{= {\min\begin{pmatrix}{\left\lceil \frac{O \cdot M_{sc}^{{PUSCH} - {initial}} \cdot N_{symb}^{{PUSCH} - {initial}} \cdot \left( {N_{{layer},1} + N_{{layer},2}} \right)}{\frac{\sum\limits_{r = 0}^{C_{1} - 1}\; K_{r,1}}{\beta_{1}} + \frac{\sum\limits_{r = 0}^{C_{2} - 1}\; K_{r,2}}{\beta_{2}}} \right\rceil,} \\{4 \cdot M_{sc}^{PUSCH} \cdot \left( {N_{{layer},1} + N_{{layer},2}} \right)}\end{pmatrix}}} \\{= {\min\begin{pmatrix}{\left\lceil \frac{O \cdot M_{sc}^{{PUSCH} - {initial}} \cdot N_{symb}^{{PUSCH} - {initial}} \cdot \left( {N_{{layer},1} + N_{{layer},2}} \right) \cdot \beta_{offset}^{PUSCH}}{{\sum\limits_{r = 0}^{C_{1} - 1}\; K_{r,1}} + {\sum\limits_{r = 0}^{C_{2} - 1}\; K_{r,2}}} \right\rceil,} \\{4 \cdot M_{sc}^{PUSCH} \cdot \left( {N_{{layer},1} + N_{{layer},2}} \right)}\end{pmatrix}}}\end{matrix}$The last step shown above assumes that the two codewords use the sameoffset value (β). MPR_(n) (n=1, 2) is the spectral efficiency associatedto the MCS level of codeword n. To derive this formula, a weighted (bynumber of layers of each codeword) average MPR may be used to calculatethe number coded symbols for the control information while the originalformula of LTE Release-8 uses the MPR of a single codeword. In addition,an order of mapping resource elements across layers and codewords needto be defined. In order to achieve diversity gain, the mapping may befirst made across codewords/layers. In the case that differentmodulation levels are used in the two codewords, coding scheme ofACK/NACK and RI need to be modified.

CQI for all Codewords:

$Q^{\prime} = {\min\begin{pmatrix}{\left\lceil \frac{\begin{matrix}{\left( {O + L} \right) \cdot M_{sc}^{{PUSCH} - {initial}} \cdot N_{symb}^{{PUSCH} - {initial}} \cdot} \\{\left( {N_{{layer},1} + N_{{layer},2}} \right) \cdot \beta_{offset}^{PUSCH}}\end{matrix}}{{\sum\limits_{r = 0}^{C_{1} - 1}\; K_{r,1}} + {\sum\limits_{r = 0}^{C_{2} - 1}\; K_{r,2}}} \right\rceil,} \\{{M_{sc}^{PUSCH} \cdot N_{symb}^{PUSCH} \cdot \left( {N_{{layer},1} + N_{{layer},2}} \right)} - {Q^{\prime}}_{RI}}\end{pmatrix}}$In addition, the order of mapping resource elements across layers andcodewords need to be defined. In order to achieve diversity gain, themapping may be first made across codewords/layers. In the case thatdifferent modulation levels are used in the two codewords, performanceneed to be verified.Furthermore, rank dependent offset values may be considered for allcases where different values of the offset β may be configured fordifferent number of layers of PUSCH transmission.

Comparison of Options.

In Table 1, the pros and cons of single codeword and all codewordmapping options are compared considering a variety of combinations. Thecomparison shows that single codeword options may be a simpler solutionthan the all codeword options.

TABLE 1 Comparison of Single-CW strategy with All-CW strategy underassumption of (a) layer shifting vs no layer shifting and (b) MMSEreceiver vs SIC receiver. LS with ANB No LS and ANB MMSE Single- Due toANB, balancing the Need to select a CW receiver CW FER performance ofthe 2 for multiplexing. CWs need to be considered. All- Same/similar MCSlevel is Different MCS levels CWs likely for both CWs. Due to are likelyfor the 2 CWs ANB, balancing the FER which make it difficult performanceof the 2 CWs to determine the number should be easy for this of codedsymbols for the setting. control information. SIC Single- Selecting CWfor multi- Selecting CW for receiver CW plexing could be tricky.multiplexing could Due to ANB, balancing be tricky. the FER performanceof the 2 CWs need to be considered. All- Different MCS levels mayDifferent MCS levels CWs be used for the 2 CWs which are likely for the2 make it difficult to determine CWs which make it the number of codedsymbols difficult to determine for the control information. In thenumber of coded addition, multiplexing control symbols for the controlin both CWs may interrupt the information. In addi- SIC receiverbehavior. Due to tion, multiplexing con- ANB, balancing the FER per-trol in both CWs may formance of the 2 CWs need interrupt the SIC to beconsidered. receiver behavior.

Advantageous features of embodiments of the invention may include: amethod for transmitting control symbols and data symbols on multipleMIMO layers, the method comprising: selecting a first set of codewordsassociated with a first set of layers from the multiple MIMO layers fromN_(cw) codewords, wherein the N_(cw) codewords are to be transmittedsimultaneously and the first set of codewords comprises N_(cw1) MIMOcodewords, where N_(cw1) is an integer greater than or equal to 1;distributing control symbols onto the first set of layers; placing datasymbols of the first set of codewords onto the first set of layers;placing data symbols of the (N_(cw)-N_(cw1)) remaining codewords toremaining layers if N_(cw)>N_(cw1); and transmitting the multiple MIMOlayers. The method could further include, wherein the first set ofcodewords comprises a single codeword. The method could further include,wherein the first set of codewords is selected by a communicationsdevice. The method could further include, wherein the first set ofcodewords is selected based on channel quality. The method could furtherinclude, wherein the first set of codewords is selected based on amodulating and coding scheme (MCS) level associated with the codewords.The method could further include, wherein the first set of codewords isselected based on the number of layers associated with the codewords.The method could further include, wherein the first set of codewords isselected based on a level of impact the control symbols have on theperformance of the data transmission of each codeword. The method couldfurther include, wherein the impact is a proportion of control symbolsto data symbols for each codeword. The method could further include,wherein the first set of codewords is selected based on a hybridautomatic repeat request (HARQ) transmission status associated with thecodewords. The method could further include, wherein the first set ofcodewords is selected by a controller serving a communications device.The method could further include, wherein the first set of codewords issignaled to the communications device via a downlink message. The methodcould further include, wherein the first set of codewords comprisesN_(cw) codewords. The method could further include, wherein distributingcontrol symbols onto the first set of layers is based on the MCS levelsof the first set of codewords. The method could further include, whereindistributing control symbols onto the first set of layers is based on aweighted MCS levels of the first set of codewords. The method couldfurther include, wherein distributing control symbols onto the first setof layers comprises distributing control symbols substantially equallyonto the first set of layers. The method could further include, whereinselecting a first set of codewords comprises selecting two differentfirst set of codewords for two different types of control symbols.

Although the embodiments and their advantages have been described indetail, it should be understood that various changes, substitutions andalterations can be made herein without departing from the spirit andscope of the invention as defined by the appended claims. Moreover, thescope of the present application is not intended to be limited to theparticular embodiments of the process, machine, manufacture, compositionof matter, means, methods and steps described in the specification. Asone of ordinary skill in the art will readily appreciate from thedisclosure of the present invention, processes, machines, manufacture,compositions of matter, means, methods, or steps, presently existing orlater to be developed, that perform substantially the same function orachieve substantially the same result as the corresponding embodimentsdescribed herein may be utilized according to the present invention.Accordingly, the appended claims are intended to include within theirscope such processes, machines, manufacture, compositions of matter,means, methods, or steps.

1. A method for multiplexing data symbols and control symbols of atleast one codeword onto a plurality of multiple input, multiple output(MIMO) layers, the method comprising: determining a number of thecontrol symbols for each of the plurality of MIMO layers by configuringa variable rank dependent offset of the at least one codeword.
 2. Themethod of claim 1, wherein the control symbols are multiplexed tosubstantially similar resource elements across the MIMO layers.
 3. Themethod of claim 1, further comprising the step of: multiplexing a firsttype of the control symbols onto a first set of the MIMO layers and asecond type of the control symbols onto a second set of the MIMO layers,wherein the first set of the MIMO layers is at least partially differentfrom the second set of the plurality of MIMO layers.
 4. The method ofclaim 3, further comprising a step of: selecting a codeword for thefirst type of the control symbols according to the codeword's Modulationand Coding Scheme (MCS) level.
 5. The method of claim 1, wherein the atleast one codeword includes a plurality of codewords, the method furthercomprising the step of: multiplexing a first type of the control symbolsonto a first set of the codewords and a second type of the controlsymbols onto a second set of the codewords, wherein the first set of thecodewords is at least partially different from the second set of thecodewords.
 6. The method of claim 1, further comprising the step of:selecting a codeword for the data symbols and the control symbols inaccordance with a hybrid automatic repeat request (HARQ) transmissionstatus.
 7. The method of claim 1, wherein the control symbols compriseat least one of channel quality information (CQI) and precoding matrixindicators (PMI).
 8. The method of claim 1, wherein the control symbolscomprise at least one of hybrid automatic repeat requested (HARQ)positive acknowledgement (ACK)/negative acknowledgement (NACK) signals,and rank indicator (RI) signals.
 9. The method of claim 1, wherein thecontrol symbols are time division multiplexed with the data symbols totime-align the control symbols across the MIMO layers.
 10. A method fortransmitting control symbols and data symbols on multiple input,multiple output (MIMO) layers, the method comprising: multiplexing datasymbols and control symbols of at least one codeword onto a plurality ofmultiple input, multiple output (MIMO) layers, and determining a numberof the control symbols for each of the plurality of MIMO layers byconfiguring a variable rank dependent offset of the at least onecodeword; and transmitting the data symbols and control symbols on theplurality of MIMO layers on an uplink channel.
 11. A system fortransmitting control symbols and data symbols of at least one codewordonto a plurality of multiple input, multiple output (MIMO) layers, thesystem comprising: a transmitter configured to determine a number of thecontrol symbols for each of the plurality of MIMO layers by configuringa variable rank dependent offset of the at least one codeword, thetransmitter including a plurality of antennas for transmitting thecontrol symbols and data symbols on the MIMO layers.
 12. The system ofclaim 11, wherein the transmitter is further configured to multiplex thecontrol symbols to substantially similar resource elements across theMIMO layers.
 13. The system of claim 11, wherein the transmitter isfurther configured to multiplex a first type of the control symbols ontoa first set of the MIMO layers and a second type of control symbols ontoa second set of the MIMO layers, and the first set of the MIMO layers isat least partially different from the second set of the MIMO layers. 14.The system of claim 13, wherein the transmitter is further configured toselect a codeword for the first type of the control symbols according tothe codeword's Modulation and Coding Scheme (MCS) level.
 15. The systemof claim 11, wherein the transmitter is further configured to multiplexa first type of control symbols onto a first set of the codewords and asecond type of control symbols onto a second set of the codewords, andthe first set of the codewords is at least partially different from thesecond set of the codewords.
 16. The system of claim 11, wherein thetransmitter is further configured to select a codeword for data symbolsand control symbols based on a hybrid automatic repeat request (HARQ)transmission status.
 17. The system of claim 11, wherein the controlsymbols comprise at least one of channel quality information (CQI),precoding matrix indicators (PMI).
 18. The system of claim 11, whereinthe control symbols comprise at least one of hybrid automatic repeatrequested (HARQ) positive acknowledgement (ACK)/negative acknowledgement(NACK) signals, rank indicator (RI) signals.
 19. The system of claim 11,wherein the antennas transmit the data symbols and control symbols onthe plurality of MIMO layers on uplink channel.